1. Field of the Invention
The present invention provides an imaging module disposed on a projection system to project an image at an appropriate display ratio.
2. Descriptions of the Related Art
With the advancement of information technology and increase in digital data, digital devices for displaying digital data have also been rapidly developing. For example, projection systems have been created to receive digital data input from an external digital device and project a larger image for easier viewing. In some cases, projection systems may further provide a richer entertainment experience, such as being used to project video games or movie pictures. Thus, projection systems have become popular display apparatuses that are commonly applied to digital devices.
Generally, digital data is set to be displayed at a specific display ratio. Digital data is mostly displayed at a display ratio (i.e., a ratio of a horizontal length to a vertical width of an image corresponding to the digital data) of 4:3 or 16:9. However, depending on the requirements of the user in creating or recording digital data, digital data (especially in the case of an image pattern) transmitted from a digital device often has to be rotated 90° before being played. For example, an original display ratio of 4:3 or 16:9 would need to be changed to a new display ratio of 3:4 or 9:16. But due to the limitation of output modes of digital devices, the length and width of the image pattern will be scaled down at equal ratios, which inevitably compromise the magnified display result of the projection system.
For example, as shown in FIGS. 1A and 1B, a projection system projects digital data with a display ratio of 4:3 as the first image 1. In this case, to display the first image 1 on a projection screen at a size as large as possible, the projection system magnifies the length and width thereof to a first length a and a first width b (as shown in FIG. 1A) which corresponds to the magnification limits of the projection system at a given location (i.e., the first image 1 is adapted to cover the entire projection screen without any spare display areas remaining on the screen). On the other hand, when the first image 1 is rotated 90° for projection as a second image 1′ with a display ratio of 3:4 due to the limitation of the internal magnification mechanism of the projection system, the first width b is used as a second width d of the second image 1′ while a second length c of the second image 1′ is scaled down accordingly as shown in FIG. 1B. Consequently, the magnification factor of the second image 1′ is much smaller than that of the first image 1. Meanwhile, because the second image 1′ is projected on a central area of the visible range of the projection screen X, shadows (as shown by the hatched portions in FIG. 1B) will appear in areas at both the left and the right sides of the projection screen X, making it impossible to obtain a desirable projection effect for the image pattern. However, to sufficiently use the magnification capacity of the projection system, the second image 1′ with the display ratio of 3:4 would be modified by a software to fill up the projection screen with a ratio of 4:3, i.e., the first image 1 would be rotated 90° while still maintaining the original display ratio of 4:3 as shown in FIG. 1C, while the second image 1′ would be extended in the lateral direction to form a deformed third image 1″, leading to an incorrect display ratio and consequently a degraded viewing effect of the image. Another way to solve this problem is to directly change the orientation in which the projection system is positioned to overcome the limitation of the magnification mechanism. For instance, the projection system originally positioned in the horizontal orientation may be rotated to a vertical orientation to project a fourth image 1′″ that is rotated 90° accordingly as shown in FIG. 1D, thus obtaining an image with a display ratio reciprocal to the original display ratio. However, to project images of the original display ratio again, the user has to revert the projection system to the original horizontal orientation, which is inconvenient and makes the projection system unstable due to the small seating area in the vertical orientation. Besides the inconvenience and instability associated with changing the positioning orientation of the projection system, the bulb of the projection system needs to also be used at a particular angle. An improper rotation of the projection system may cause shortened service life of or damage to the wick. Moreover, this also has an adverse influence on heat dissipation in the projection system. More specifically, the thermal module inside the projection system is designed according to the original positioning orientation of the projection system, so the air flows from the fan in a certain direction determined by the vent holes formed in the housing of the projection system. Unfortunately, rotating the positioning orientation of the projection system might block the vent holes, which compromise the effect of forced convection provided by the cooling fan, thus causing poor heat dissipation. Consequently, because waste heat generated by components inside the projection system (especially the bulb) cannot be dissipated out of the projection system successfully and effectively, the accumulation of the waste heat within the projection system might damage to the projection system and shorten the service life thereof. Therefore, the abovementioned practice for adjusting images is infeasible.
It follows from the above description that when an image pattern from an existing digital device is to be rotated 90° before being projected via a projection system, the length and width of the image must be scaled down at equal ratios to keep the original display ratio of the image pattern. However, no effective solutions have been provided to increase the magnification factor of the image. Accordingly, it is important to develop a projection system that provides an increased magnification factor under normal use conditions while still maintaining the original display ratio (mostly of 3:4 or 9:16) of the projected image.